Diabetes affects nearly 26 million people in the U.S. and over 62 million in India, placing these nations second and third in the world in terms of population burden of diabetes. Diabetes is reported as increasing in younger age groups both in India and the US, with long-term implications for burden of complications, health care costs, and risk of diabetes in future generations. In 2000, the Indian Council of Medical Research (ICMR) established the Registry of People with Diabetes with Young Age at Onset (YDR), including youth and young adults less than 25 years of age from eight sites across India. In the U.S., the SEARCH for Diabetes in Youth study is a multicenter epidemiologic study conducting population-based case ascertainment of youth with diabetes before age 20 years since 2001, currently in five locations across the U.S. However, the ability to compare the epidemiologic characteristics of diabetes in youth between India and the U.S. is at present lacking. Knowledge of whether prevalence, incidence, mortality, and clinical presentation, treatment, quality of care and quality of life differ can lead to new insights into the potential causes and improved treatment. A sensitive surveillance system in both countries can also inform policy about whether changes in underlying risk factors such as obesity, environmental exposures and other factors are leading to an increase in risk, or whether improved nutrition and environmental hygiene have reduced risk over time. These challenges have been identified by the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) and the ICMR who sponsored an Indo-U.S. workshop titled Innovative Approaches and Technologies for Diabetes Prevention and Management, held on February 4-6, 2013, in New Delhi. In response to the recent NIDDK funding opportunity announcement (FOA) we propose to conduct preliminary harmonization work of U.S. and Indian registries of childhood diabetes to address several specific aims: AIM 1: To harmonize the Indian YDR and the SEARCH registry in the U.S. AIM 2: To compare phenotypic, clinical and demographic characteristics by type of diabetes between YDR and SEARCH. AIM 3: To compare the burden of diabetes in youth by age, sex, race/ethnicity and type of diabetes between India and the US. Harmonization of the SEARCH and YDR registries is a critical step towards building capacity to understand global trends. This application is significant in proposing to harmonize registries covering both T1 and T2D at a critical moment in history when trends in diabetes are dynamic yet poorly understood from a global perspective.